Make run_remote_test's use of ssh-agent more predictable.

src/scripts/remote_access.sh

 # Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Library for setting up remote access and running remote commands.
 
 DEFAULT_PRIVATE_KEY="${GCLIENT_ROOT}/src/scripts/mod_for_test_scripts/\
 ssh_keys/testing_rsa"
 
 DEFINE_string remote "" "remote hostname/IP of running Chromium OS instance"
 DEFINE_string private_key "$DEFAULT_PRIVATE_KEY" \
   "Private key of root account on remote host"
 
 function remote_sh() {
   REMOTE_OUT=$(ssh  -o StrictHostKeyChecking=no -o \
     UserKnownHostsFile=$TMP_KNOWN_HOSTS root@$FLAGS_remote "$@")
   return ${PIPESTATUS[0]}
 }
 
 function remote_sh_allow_changed_host_key() {
   rm -f $TMP_KNOWN_HOSTS
   remote_sh "$@"
 }
 
 function set_up_remote_access() {
   if [ -z "$SSH_AGENT_PID" ]; then
     eval $(ssh-agent)
+    OWN_SSH_AGENT=1
+  else
+    OWN_SSH_AGENT=0
   fi
   cp $FLAGS_private_key $TMP_PRIVATE_KEY
   chmod 0400 $TMP_PRIVATE_KEY
   ssh-add $TMP_PRIVATE_KEY
 
   # Verify the client is reachable before continuing
   echo "Initiating first contact with remote host"
   remote_sh "true"
   echo "Connection OK"
 }
 
+function cleanup_remote_access() {
+  # Call this function from the exit trap of the main script.
+  # Iff we started ssh-agent, be nice and clean it up.
+  # Note, only works if called from the main script - no subshells.
+  if [[ 1 -eq ${OWN_SSH_AGENT} ]]
+  then
+    kill ${SSH_AGENT_PID} 2>/dev/null
+    unset SSH_AGENT_PID SSH_AUTH_SOCK
+  fi
+}
+
 function remote_access_init() {
   TMP_PRIVATE_KEY=$TMP/private_key
   TMP_KNOWN_HOSTS=$TMP/known_hosts
   if [ -z "$FLAGS_remote" ]; then
     echo "Please specify --remote=<IP-or-hostname> of the Chromium OS instance"
     exit 1
   fi
   set_up_remote_access
 }